1. Field of the Invention
This invention relates to the field of communications network resource conservation systems. More specifically, this invention relates to a way in which network bandwidth is conserved and voice quality can be improved.
2. Description of Problem Solved
H.323 series of standards by the International Telecommunication Union (ITU) specify how telephony services can be offered on a Local Area Network (LAN) or Internet without guaranteed quality of service. H.323 clients can talk to each other using H.225 as call control signaling and H.245 as the channel control protocol. Voice-over-Internet-Protocol (VoIP) is a way to offer existing voice telephony services to H.323 clients. This invention provides an algorithm by which the H.323 clients can talk to each other directly via the packet based network even though the call was initially routed through the Switched Circuit Network (SCN), hence conserving the network sources and potentially improving the voice quality. The voice quality improvement will be apparent when both parties are on the same LAN and both parties are far away from the serving Public Switched Telephone Network (PSTN) switch. The two H.323 clients must transfer voice data via the telephone switch and the PSTN, even though the telephone switch is located at a remote location far away from the H.323 clients, and the H.323 clients are located on a common LAN or located on separate LANs that are linked via the Internet. A disadvantage of routing the voice through the telephone switch and the PSTN is that Network bandwidth is being wasted and voice quality is negatively impacted unnecessarily when two H.323 clients are talking through the PSTN if the two H.323 clients can make a direct communication connection via their networks.
What is needed is to provide a way by which users of H.323 terminal devices can talk to each other directly via a packet based network, i.e., the Internet, even though the call will be initially setup through the telephone switch and the PSTN and obtain all the supplementary services from the switch; hence conserving the PSTN resources and improving voice quality. Essentially, the bearer channel or basic telephone communications channel is established via the network and not through the telephone switch and the PSTN, thus limiting the number of times data must be converted to and from voice and packet data when being transferred between users as in a normal call. The voice quality improvement between linked users will be apparent when both parties are on the same LAN and both parties are far away from the serving telephone switch. In addition, Network bandwidth is being wasted by assigning communications channels via the PSTN. Furthermore, the communications system must be able to revert an existing call that is directly connected via the network, back through the telephone switch and the PSTN at the request of a user without interrupting the existing communications session via the packet based network.
Thus, an object of this invention is to provide a way by which H.323 clients can talk to each other directly via the packet based network, even though a call is initially setup through the telephone switch and the PSTN.
It is another object of this invention to conserve the resources of the PSTN by establishing data communications sessions directly via packet based networks, thus reserving network bandwidth and communications channels in the PSTN.
It is a further object of this invention to improve the quality of voice sessions when two H.323 clients are on the same LAN or on separate LANs that are networked, and both are far away from the serving telephone switch.
It is still a further object of this invention to minimize the number of times data is translated to and from voice and packet data between two H.323 clients.
The present invention solves the above problems by providing telecommunications infrastructures that can directly establish a voice path between two users via their LAN(s), thus not routing the voice path through the telephone switch and the PSTN as for a typical telephone call and yet get supplementary services from the PSTN switch. The telephone call will be setup through the telephone switch and the PSTN as for a normal call. However, the bearer channels will be established directly between the calling party and the called party via their LAN(s). Essentially, the calling party will initiate a call to the called party via an H.323 terminal device. When the setup messages from the calling party is routed through the telephone switch to setup the call, the telephone switch will determine whether the initiated call can be Intraswitched via the calling and called parties"" LAN(s). Essentially, the telephone switch must determine whether a basic call has been requested and whether the calling party and called party both have H.323 terminal devices, capable of establishing a phone call, that are networked together. If so, the telephone switch will send messages to the calling party and the called party instructing them to open communications channels via their LAN(s). The calling party and the called party then establish a voice path via their LAN(s).
The present invention also provides a way to invoke supplemental features of telephony service, such as flexible calling, three way calling, etc. Since the telephone switch must be used to invoke supplemental features, the invention provides a way to revert an Intraswitched call through the telephone switch automatically when needed. Either party can notify the telephone switch that it wishes to use a supplemental feature. The telephone switch will determine whether the call must be reverted through the telephone switch and the PSTN to provide the requested supplemental service. If the call must be reverted, the telephone switch will automatically establish a communications channel between the calling and called parties through the telephone switch and the PSTN as in a normal telephone call. Once the call has been routed through the telephone switch and the PSTN, the two parties disconnect their current communications connection that is already Intraswitched through their LAN(s), without interrupting the existing communications session via the telephone switch and the PSTN.